Sequential assembly of PEDOT/BiVO₄/FeOOH onto cotton fabrics for photocatalytic degradation of reactive dyes

This paper demonstrates that a multilayered absorbent developed using Poly(3,4-ethylenedioxythiophene) (PEDOT) modified cotton fabrics provides excellent photocatalytic degradation and remove dyes in wastewater. Low cost, highly efficient and biobased sorbents for removing dyes and other pollutants in wastewater are desirable. However, there are very few absorbents that meet these criteria. Bismuth vanadate (BiVO₄) is a unique material with strong visible light absorption and valence band potential suitable for the degradation of dyes. However, the photogenerated carriers of single BiVO₄ get recombined easily, and it is difficult to recover the powder which may cause secondary pollution. To overcome this limitation, we have successfully prepared a composite containing PEDOT/BiVO₄/Iron oxide hydroxide (FeOOH) on cotton fabrics in a simple two-step process. Initially, cotton fabrics were treated with PEDOT and later BiVO₄/FeOOH onto the modified fabrics. When the cotton-based composite was used as sorbent for reactive brilliant blue dye (RB-19), a high degradation level of 95.6% was possible within 2 h under visible light. Further, the sorbent had high recyclability of 92.3% even after 5 sorption and desorption cycles. The experiment suggests that the presence of h⁺ and ·OH free radicals along with excellent electron-hole transport properties of PEDOT were responsible for the high level of degradation.